Porous Ceramic Electrolyte Layer for Gas Sensor Ion Migration
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Solution Overview
Problem
Existing electrochemical sensors for measuring gaseous analytes in aqueous media face challenges with short service life, interference from ions, and high production costs due to thin polymer layers and ion migration issues, which affect their longevity and accuracy.
Innovation Solution
The development of an electrochemical sensor with a porous, non-swellable framework structure comprising particulate material and a binder, forming pores of specific diameters and absorption rates, which increases the distance ions must travel and reduces ion migration, combined with a gas-permeable cover layer to prevent ion entry, and a liquid electrolyte containing alkali metal chloride and pH buffers to stabilize the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thin polymer electrolyte layer is used, then the sensor dimensions are reduced, but ion migration increases and service life decreases
Solution Approach 1:
The patent replaces the thin polymer electrolyte layer with a porous ceramic electrolyte layer that has controlled pore sizes (0.1-10 μm). The porous structure provides tortuous ion pathways that increase the effective ion migration distance despite the layer being thin (5-50 μm), thereby reducing ion migration while maintaining compact sensor dimensions and long service life.
2Reliability
If the electrolyte layer thickness is increased, then ion migration is reduced, but the sensor dimensions and sample volume requirement increase
Solution Approach 1:
The porous ceramic electrolyte layer with controlled pore sizes creates a tortuous path for ion migration. This allows the electrolyte layer to be thin (5-50 μm) while still providing sufficient ion migration resistance, as the ions must navigate through the porous structure rather than moving in a straight line, thus reducing the required thickness compared to non-porous materials.
3Measurement precision
If a gas-permeable membrane is used to separate the reaction space, then gas analyte measurement is enabled, but ion interference from the aqueous medium occurs
Solution Approach 1:
The porous ceramic electrolyte layer serves a dual function: it acts as the electrolyte medium for ion conduction between electrodes while simultaneously serving as the ion barrier to the aqueous measurement medium. The controlled porosity allows gas molecules to pass through while the ceramic material's properties prevent ion penetration from the aqueous phase, thus enabling gas analyte measurement without ion interference.
4Quantity of substance
If multiple parameters are measured with small sample volumes, then the electrode dimensions must be minimized, but manufacturing precision requirements increase
Solution Approach 1:
The porous ceramic electrolyte layer can be applied as a thin, uniform coating (5-50 μm) over the electrodes using techniques such as screen printing, dip-coating, or spray application. The porous structure allows for controlled material deposition that maintains consistency even at small dimensions, enabling miniaturized electrodes for small sample volume measurements while managing manufacturing precision requirements through appropriate application techniques.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the sensor's service life, reduces interference, and maintains accuracy over multiple measurements, while being cost-effective and easy to manufacture.
Implementation Method 1
the pores of the non-swellable framework structure being intended for receiving a liquid electrolyte or containing it, and (i) the pores of the non-swellable framework structure have a diameter of about 500 nm to about 5 μm, in particular from about 1 μm to about 3 μm, or/and (ii) the porous, non-swellable framework structure has a relative liquid absorption of about 20% to about 50% by weight
Implementation Method 2
a gas-permeable cover layer, which serves to spatially separate the working electrode, the counter-electrode and the electrolyte layer from the aqueous measurement medium
Implementation Method 3
the pH value, which is determined by the respective pCO 2 value of the sample to be measured, is measured in this reaction chamber
Implementation Method 4
at least one of the electrodes representing the working electrode at which the analyte to be determined is electrochemically changed (e.g. oxidized or reduced)
Implementation Method 5
a liquid electrolyte containing alkali metal chloride and pH buffers to stabilize the sensor
Data Source
Figure 1A~1B
Figure 2~3B
Figure 4~5
AI summary
The present invention relates to electrochemical sensors for determining gaseous analytes dissolved in an aqueous measuring medium, to a process for producing said sensors, and to a process for determining gaseous analytes dissolved in an aqueous measuring medium using the electrochemical sensors. The electrolyte layer of the sensors comprises at least one particulate material and at least one binder which together form a porous, non-swellable framework structure, wherein the pores in this framework structure are intended for receiving a liquid electrolyte or contain the latter.